This application relates to safety features for a low pressure turbine in a geared turbofan.
Gas turbine engines are known and typically include a fan delivering air into a bypass duct as propulsion air and into a compressor as core airflow. The air is compressed in the compressor and delivered into a combustor where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors driving them to rotate.
Historically, a fan drive turbine rotated at a single speed with the fan. However, there were limitations on the design and operation due to this restriction. Thus, it has been proposed to incorporate a gear reduction between the fan and the fan drive turbine. The assignee of this application has recently developed production gas turbine engines which incorporate such a gear reduction.
It has also been proposed to incorporate the gear reduction between the fan drive turbine and a low pressure compressor that is also driven by the fan drive turbine. With such an engine, challenges are raised should the shaft from the fan drive turbine fail. There is no longer a compressor slowing speed of rotation of the fan drive turbine once the shaft has failed.